Handbook of Veterinary Procedures and Emergency Treatment_2 ppt

ROUTINE PROCEDURES ADMINISTRATION TECHNIQUES FOR MEDICATIONS AND FLUIDS O RAL ADMINISTRATION: TABLETS/CAPSULES—CANINE Perhaps the simplest and easiest method of administering tablets or capsules to dogs is to hide the medication in food. Offer small portions of unbaited cheese, meat, or some favorite food to the dog initially. Then offer one portion that includes the medication. SECTION 4 Diagnostic and Therapeutic Procedures Routine Procedures, 449 Administration Techniques for Medications and Fluids, 449 Bandaging Techniques, 462 Blood Pressure Measurement: Indirect, 462 Central Venous Pressure Measurement, 463 Diagnostic Sample Collection Techniques, 465 Dermatologic Procedures, 489 Ear Cleaning: External Ear Canal, 492 Endotracheal Intubation, 494 Intravenous Catheterization, 495 Physical Therapy, 497 Advanced Procedures, 500 Abdominocentesis, 500 Biopsy Techniques: Advanced, 501 Blood Gas: Arterial, 508 Cerebrospinal Fluid Collection, 509 Electrocardiography, 511 Endoscopy: Indications and Equipment Requirements, 518 Fluid Therapy, 523 Gastrointestinal Procedures, 526 Laparoscopy, 532 Ophthalmic Procedures, 535 Radiography: Advanced Contrast Studies, 541 Reproductive Tract: Female, 549 Reproductive Tract: Male, 554 Respiratory Tract Procedures, 559 Urinary Tract Procedures, 571 449 A03751-S04 11/11/05 4:13 PM Page 449 For anorectic dogs or when pills must be given without food, give medications quickly and decisively so that the process of administering the medication is accomplished before the dog realizes what has happened.With cooperative dogs, insert the thumb of one hand through the interdental space, and gently touch the hard palate. This will cause the dog to open the mouth (Figure 4-1). Using the opposite hand (the one holding the medication), gently press down on the mandibular (lower) incisors to open the mouth further (Figure 4-2). Position the tablet or capsule onto the caudal aspect of the tongue as close to the larynx as possible. Quickly withdraw the hand and close the dog’s mouth. When the dog licks its nose, the medication likely has been swallowed. Note: Oral medication frequently is dispensed to owners without regard for the client’s knowledge of how to administer a pill/tablet or without asking whether the client is even physically able to administer medications. Clear instructions, including a demonstration, and having the client perform the technique in the hospital will improve compliance. Dogs that offer more resistance can be induced to open their mouths by compressing their upper lips against their teeth. As they open their mouth, roll their lips medially so that if they attempt to close their mouth, they will pinch their own lips. Dogs that struggle and slash with their teeth are the most difficult, especially if they show aggression toward the individual attempting to administer mediation. They often can be medicated by placing the tablet over the base of the tongue with a 6-inch curved Kelly hemostat or special pill forceps. Cubes of canned food or dried meat often can be “pushed down” a placid but anorectic patient by using the thumb as a lever. The fingers are kept out of the mouth, but the thumb is inserted behind the last molar of the open mouth and pushes the bolus down. 450 4 DIAGNOSTIC AND THERAPEUTIC PROCEDURES Figure 4-1: Use of the thumb only to open a cooperative dog’s mouth. A03751-S04 11/11/05 4:13 PM Page 450 ORAL ADMINISTRATION: TABLETS/CAPSULES-FELINE Two methods of pill administration are used in cats. In both methods the cat’s head is elevated slightly. Success in administering pills/tables to a cat entails a delicate balance between what works well and what works safely. In cooperative cats, it may be possible to use one hand to hold and position the head (Figure 4-3) while using the opposite hand (the one holding the medication) to open the mouth gently by depressing the proximal aspect of the mandible (Figure 4-4). Press the skin adjacent to the maxillary teeth gently between the teeth as the mouth opens, thereby discouraging the cat from closing its mouth. With the mouth open, drop the medication (try lubricating the tablet or capsule with butter) into the oral cavity as far caudally on the tongue as possible. The cat can be tapped under the jaw or on the tip of the nose to facilitate swallowing if you really think this works. If the cat licks, administration was probably successful. CAUTION: Only experienced individuals should attempt this technique of administer- ing tablets/capsules to cats. Even cooperative cats that become intolerant will bite. Therefore, this is NOT a technique recommended for inexperienced owners to try at home, even if specific instructions have been given. Alternatively, some cats will tolerate a specially designed “pilling syringe” in an attempt to administer a tablet or capsule. The pilling syringe works well as long as it is inserted cautiously and atraumatically into the cat’s mouth. However, if resistance ensues, the rigid pilling syringe may injure the hard palate during the ensuing struggle. Subsequent attempts to use the syringe may be met with increasing resistance and increasing risk of injury. Success with a pilling syringe depends largely on the cat. When dispensing oral medications for home administration to cats, do not expect clients to force a tablet or capsule into a cat’s mouth. Although some clients are remarkably capable and confident with their ability to administer oral medications to cats, the risk of injury to the client can be significant. Whenever feasible, liquid medications or pulverized ROUTINE PROCEDURES 451 Figure 4-2: Use of the opposite hand to place a tablet or capsule on the caudal aspect of the tongue. A03751-S04 11/11/05 4:13 PM Page 451 452 4 DIAGNOSTIC AND THERAPEUTIC PROCEDURES 4 Figure 4-3: Head restraint technique used while administering a tablet/capsule to a cat. Figure 4-4: Use of the opposite hand gently to depress a cat’s mandible before dropping a tablet into the caudal aspect of the oral cavity. A03751-S04 11/11/05 4:13 PM Page 452 tablets should be mixed with the diet or an oral treat readily accepted and consumed (see the following discussion). O RAL ADMINISTRATION: LIQUIDS Without a stomach tube Small amounts of liquid medicine can be given successfully to dogs and cats by pulling the commissure of the lip out to form a pocket (Figure 4-5). Hold the patient’s head level so that the medication will not ooze into the larynx. Deposit the liquid medication into the “cheek pouch” where it subsequently flows between the teeth as the head is held slightly upwards. Patience and gentleness, along with a reasonably flavored medication, are needed for success. Spoons are ineffective because they measure fluids inaccurately and materials spill easily. A disposable syringe can be used to measure and administer liquids per os. Depending on the liquid administered, disposable syringes can be reused several times, assuming they are rinsed following each administration. In addition, disposable syringes can be dispensed legally to clients for home administration of liquid mediation. Mixing of medications in the same syringe is not recommended. However, dispensing of a separate, clearly marked syringe for each type of liquid medication prescribed for home administration is recommended. With an administration tube Administration of medications, contrast material, and rehydrating fluids can be accom- plished with the use of a feeding tube passed through the nostrils into the stomach or distal esophagus. Today, the general recommendation is to avoid passing the tip of a feeding tube beyond the distal esophagus. This is particularly true when a feeding tube is placed for long-term and repeated use (described in Gastrointestinal Procedures in this section). The reason for recommending nasoesophageal intubation over nasogastric intubation is based on the additional risk of irritation and even ulceration of the esophageal mucosa at the ROUTINE PROCEDURES 453 4 Figure 4-5: Use of a syringe to administer liquid medication into the oral cavity of a cat. A03751-S04 11/11/05 4:13 PM Page 453 level of the cardia. Reflex peristalsis of the esophagus against a tube passing through the cardia has resulted in significant mucosal ulceration within 72 hours when feeding tubes were left in place. In patients receiving a single dose of medication or contrast material, nasogastric intubation is likely to be as safe as nasoesophageal intubation. The narrow lumen of tubes passed through the nostril of small dogs and cats limits the viscosity of solutions that can be administered through a tube directly into the gastroin- testinal tract. Nasoesophageal intubation can be done with a variety of tube types and sizes (Table 4-1). Newer polyurethane tubes, when coated with a lidocaine lubricating jelly, are nonirritating and may be left in place with the tip at the level of the distal esophagus. When placing the nasogastric tube, instill 4 to 5 drops of 0.5% proparacaine in the nostril of the cat or small dog; 0.5 to 1.0 mL of 2% lidocaine instilled into the nostril of a larger breed dog may be required to achieve the level of topical anesthesia needed to pass a tube through the nostril. With the head elevated, direct the tube dorsomedially toward the alar fold (Figure 4-6). After inserting the tip 1 to 2 cm into the nostril, continue to advance the tube until it reaches the desired length. If the turbinates obstruct the passage of the tube, with- draw the tube by a few centimeters. Then readvance the tube, taking care to direct the tube ventrally through the nasal cavity. Occasionally, it will be necessary to withdraw the tube completely from the nostril and repeat the procedure. In particularly small patients or 454 4 DIAGNOSTIC AND THERAPEUTIC PROCEDURES 4 TABLE 4-1 The French Catheter Scale Equivalents* Size Scale (mm) (inches) 3 1 0.039 4 1.35 0.053 5 1.67 0.066 6 2 0.079 7 2.3 0.092 8 2.7 0.105 9 3 0.118 10 3.3 0.131 11 3.7 0.144 12 4 0.158 13 4.3 0.170 14 4.7 0.184 15 5 0.197 16 5.3 0.210 17 5.7 0.223 18 6 0.236 19 6.3 0.249 20 6.7 0.263 22 7.3 0.288 24 8 0.315 26 8.7 0.341 28 9.3 0.367 30 10 0.393 32 10.7 0.419 34 11.3 0.445 *Mutiple types of pediatric polyurethane nasogastric feeding tubes are available in sizes ranging from 8F to 12F that easily accommodate administration of liquids medications and fluids to kittens, cats, and small dogs. A03751-S04 11/11/05 4:13 PM Page 454 patients with obstructive lesions (e.g., tumor) in the nasal cavity, it may not be possible to pass a tube. Do not force the tube against significant resistance through the nostril. CAUTION: The tip of the tube possibly can be introduced inadvertently through the glottis and into the trachea. Topical anesthetic instilled into the nose can anesthetize the arytenoid cartilages, thereby blocking a cough or gag reflex. I prefer to check the tube place- ment with a dry, empty syringe. Attach the test syringe to the end of the feeding tube. Rather than inject air or water in an attempt to auscultate borborygmus over the abdomen, attempt simply to aspirate air from the feeding tube. IF THERE IS NO RESISTANCE DURING ASPIRATION AND AIR FILLS THE SYRINGE, THE TUBE LIKELY HAS BEEN PLACED IN THE TRACHEA. Completely remove the tube and repeat the procedure. However, if repeated attempts to aspirate are met with immediate resistance and NO AIR ENTERS THE SYRINGE, the tube tip is positioned properly within the esophagus. If there is any question regarding placement, a lateral survey radiograph is indicated. Gavage, or gastric lavage/feeding, in puppies and kittens can be accomplished by pass- ing a soft rubber catheter or feeding tube through the nose and into the stomach. A 12F catheter is of an adequate diameter to pass freely, but it is too large for dogs and cats less than 2 to 3 weeks of age. Mark the tube with tape or a pen at a point equal to the distance from the tip of the nose to the last rib. Merely push the tube into the pharynx and down the esophagus to the caudal thoracic level (into the stomach). Attach a syringe to the flared end, and slowly inject medication or food. Use the same dry syringe aspiration technique to ensure that the tube is positioned in the esophagus/stomach rather than the trachea before administration. A less desirable but effective technique for one-time tube administration of medica- tions, food, or fluids entails passing the administration tube directly through the oral cavity and into the esophagus or stomach. However, this technique requires the use of a speculum to ensure that the patient does not bite or sever the tube with its teeth. A variety of specu- lums are available, ranging from hard rubber bite-blocks with a centrally positioned hole ROUTINE PROCEDURES 455 4 Figure 4-6: Initial dorsomedial placement of a nasoesophageal tube before complete insertion. A03751-S04 11/11/05 4:13 PM Page 455 for passing the tube to improvised speculums such as a roll of 1- to 2-inch adhesive tape positioned between the mandible and maxilla. A well lubricated 22F rubber catheter, up to 30 inches long, is an ideal tube. Attach the catheter to a syringe that delivers the medication. When the patient swallows, advance the catheter into the esophagus to the level of the eighth or ninth rib. Measure this distance on the tube first, and mark it with a ballpoint pen or a piece of tape. To pass the tube into the trachea in a conscious dog with its head held in a normal position is almost impossible. It may be possible to palpate the neck to feel the tube in the esophagus. Nasoesophageal intubation in cats is generally much better tolerated that orogastric intubation. The cat can be restrained in a bag or cat stocks or by rolling it in a blanket. The cat is held in a vertical position by an assistant. Position a mouth speculum between the mandible and maxilla. This is where the fun begins. The operator then grasps the cat’s head, as for pilling, and quickly passes the prelubricated tube 6 to 10 inches down the esophagus. A 12F to 16F soft rubber catheter, 16 inches long, makes a suitable tube. Depending on the feeding tube type, the end of the tube may or may not accommodate a syringe. For example, soft, rubber urinary catheters are excellent tubes for single administra- tion use. However, the flared end may not accommodate a syringe. To affix a syringe to the outside end of a tapered feeding tube or catheter, insert a plastic adapter (Figure 4-7) into the open end of the tube. T OPICAL ADMINSTRATION Ocular There are numerous ways to apply medication to the eyes, including the use of drops, oint- ments, subconjunctival injections, and subpalpebral lavage. The route and frequency of medication depend on the disease being treated. If more than 2 drops of aqueous material are administered, the fluid will wash out of the conjunctival cul-de-sac and be wasted. Most drops should be applied every 2 hours (or less) to maintain effect. Ointments should be applied sparingly, and their effect may last a maximum of 4 to 6 hours. Place drops on the inner canthus without touching the eye with the dropper tip. Place ointment ( 1 /8-inch-long strip) on the upper sclera or lower palpebral border so that as the lids close, they form a film across the cornea. Otic Medicated powders generally are contraindicated in the external ear canal. Thin films of ointments or propylene glycol solutions are more effective vehicles and are recommended. A few drops generally suffice, and the ear should be massaged gently after instillation to spread the medication over the external ear canal. 456 4 DIAGNOSTIC AND THERAPEUTIC PROCEDURES 4 Figure 4-7: Use of a plastic adaptor (“Christmas tree”) to affix a syringe to a nasoesophageal feeding tube. A03751-S04 11/11/05 4:13 PM Page 456 Nasal Isotonic aqueous drops are used for nasal application and should be applied without touching the dropper to the nose. Oily drops are not advised because they may damage the nasal mucosa or may be inhaled. There is little indication for routine instillation of medica- tion into the nostrils of dogs and cats. Dermatologic Several objectives should be considered when treating dermatologic disorders: (1) eradica- tion of causative agents; (2) alleviation of symptoms, such as reduction of inflammation; (3) cleansing and debridement; (4) protection; (5) restoration of hydration; and (6) reduc- tion of scaling and callus. Many different forms of skin medications are available, but the vehicle in which they are applied is a critical factor (Box 4-1). In all cases, apply topical medications to a clean skin surface in a very thin film, because only the medication in contact with the skin is effective. In most cases, clipping hair from an affected area enhances the effect of medication. Note on compounding pharmacies With the widespread availability of compounding pharmacies, prescribing compounded medications for topical and oral administration recently has become a popular dispensing technique for dogs and cats requiring long-term, daily mediation. Caution is warranted. Some compounding pharmacies that serve the veterinary profession are using inappropri- ate or ineffective vehicles in which the drug has been compounded, or the drug itself, purchased in bulk, is a lower grade and possibly an ineffective product once compounded. Studies on the quality and efficacy of compounded drugs for use in veterinary patients are limited. However, of those studies that have been performed, serious questions are being raised over the bioavailability of the drug administered. A DMINISTRATION BY INJECTION (PARENTERAL ADMINISTRATION) Before aspirating medications from multiple-dose vials, carefully wipe the rubber diaphragm stopper with the same antiseptic used on the skin. Observe this basic rule with all medication vials, even with modified live virus vaccines. It would be admirable to prepare the skin surgically before making needle punctures to administer medications. Because such preparation is not practical, carefully part the hair and apply a high-quality skin antiseptic such as benzalkonium chloride in 70% alcohol. Place the needle directly on the prepared area, and thrust the needle through the skin. Although the use of antiseptics on the vial and skin is not highly effective, the procedure removes gross contamination and projects an image of professionalism. ROUTINE PROCEDURES 457 4 BOX 4-1 VEHICLES USED IN THE ADMINISTRATION OF TOPICAL SKIN MEDICATIONS Lotions are suspensions of powder in water or alcohol. They are used for acute, eczematous lesions. Because they less easily are absorbed than creams and ointments, lotions need to be applied 2 to 6 times a day. Pastes are mixtures of 20% to 50% powder in ointment. In general, they are thick, heavy, and difficult to use. Creams are oil droplets dispersed in a continuous phase of water. Creams permit excellent percutaneous absorption of ingredients. Ointments are water droplets dispersed in a continuous phase of oil. They are very good for dry, scaly eruptions. Propylene glycol is a stable vehicle and spreads well. It allows good percutaneous absorption of added agents. Adherent dressings are bases that dry quickly and stick to the lesion. Shampoos are usually detergents designed to cleanse the skin. If shampoos are left in contact with the skin for a time, added medications may have specific antibacterial, antifungal, or antipar- asitic effects. A03751-S04 11/11/05 4:13 PM Page 457 SUBCUTANEOUS INJECTION Dogs and cats have abundant loose alveolar tissue and easily can accommodate large volumes of material in this subcutaneous space. The dorsal neck is seldom used for subcu- taneous injections because the skin is somewhat more sensitive, causing some patients to move abruptly during administration. A wide surface area of skin and subcutaneous tissue over the dorsum from the shoulders to the lumbar region makes an ideal site for subcuta- neous injections. Administration of drugs, vaccines, and fluids by the subcutaneous route represents the most commonly used route of parenteral administration in dogs and cats. For small volumes (<2 mL total), such as vaccines, a 22- to 25-gauge needle generally is used. The site most often used is the wide area of skin over the shoulders. The large subcutaneous space and the relative lack of sensitivity of skin at this location make it an ideal injection site. Cleaning of the skin with alcohol or other disinfectant generally is performed before injec- tion. Several injection techniques are used. A common technique entails grasping a fold of skin with two fingers and the thumb of one hand. Gently lift the skin upward. Using the opposite hand, place the needle, with syringe attached, through the skin at a point below the opposite thumb. Aspiration before injection is not typically necessary when using this route of administration. Following administration and on removal of the needle from the skin, gently pinch the injection site and hold it for a few seconds to prevent backflow of medication or vaccine onto the skin. When larger volumes are to be administered—fluids in dehydrated dogs and cats—the skin directly over the shoulders is the injection site most commonly selected. Generally, only isotonic fluids are administered by the subcutaneous route. Depending on the patient’s size, needles ranging from 16 to 22 gauge can be used. Because of the larger volumes of fluid involved, warming of the fluids before administration is recommended. Doing so can enhance significantly the patient’s tolerance for the displacement of skin during the period of administration. Depending on the rate of administration and breed of dog, relatively large volumes of fluid generally can be given in one location. Cats typically tolerate 10 to 20 mL/kg body mass in a single location. Large dogs can tolerate volumes greater than 200 mL of fluid in a single location. When administering large volumes, it is usually not neces- sary to use multiple injection sites for purposes of distributing the total fluid volume. Doing so actually may increase the risk of introducing cutaneous bacteria under the skin. Because the administration time required to deliver larger volumes is longer, and the injec- tion needle will be placed in the skin for extended periods, it is appropriate to cleanse and rinse the skin carefully before actually inserting the needle. Isotonic, warmed fluids may be administered by large syringe or through an administration tube attached to a bag. Monitor skin tension and the patient’s comfort tolerance throughout the procedure. Although fluid absorption begins almost immediately on subcutaneous administration of fluids, significant pressure caused by the bolus of fluid delivered can develop within the fluid pocket. On removal of the needle, firmly grasp the injection site with the thumb and forefinger for several seconds. The procedure is not complete until one has verified that back-leakage of fluid from the subcutaneous space onto the skin is not occurring. Note: Not all parenteral medications can be administered safely by the subcutaneous route. When administering any compound by the subcutaneous route, verify that the product to be administered is approved for subcutaneous administration. Serious reactions, including abscess formation and tissue necrosis, can occur. Depending on the patient’s hydration status and physical condition, fluid absorption may take from 6 to 8 hours. NOTE: The rate of absorption of fluid administered by the subcutaneous route largely depends on the patient’s hydration state and vascular and cardiac integrity. For that reason, the subcutaneous route is not recommended to manage patients in hypovolemic shock. Exceptions to this do exist, for example, when in a life-or-death situation access to a vein is 458 4 DIAGNOSTIC AND THERAPEUTIC PROCEDURES 4 A03751-S04 11/11/05 4:13 PM Page 458 [...]... to the port and administer the appropriate volume of fluids at an appropriate rate and frequency Because of the usual requirement for long-term placement of an implantable fluid administration tube, there is risk of infection under the skin and around the incision site Some cats do not tolerate the device INTRAMUSCULAR INJECTION Because the tightly packed muscular tissue cannot expand and accommodate... Additional Reading Crow S, Walshaw S: Manual of clinical procedures in the dog, cat, and rabbit, ed 2, Philadelphia, 1997, Lippincott-Raven Kirby R, Rudloff E: Crystalloid and colloid fluid therapy In Ettinger SJ, Feldman EC, editors: Textbook of veterinary internal medicine, ed 6, St Louis, 2005, Elsevier-Saunders Marks S: The principles and practical application of enteral nutrition, Vet Clin North Am... 4 DIAGNOSTIC AND THERAPEUTIC PROCEDURES FUNGAL CULTURE Diagnostic fungal cultures depend on selection of the most appropriate culture site, proper collection of specimens, and appropriate use of selective media Culture specimens from patients suspected of having superficial fungal infections (dermatophytosis) are made from hair, skin, nails, and biopsy tissues Test patients suspected of having deep... parallel to the direction of the hair growth It is important to get the hair root and not break off the hair shaft Pluck many hairs and implant (push) the roots of the hair into the selected agar Then gently lay the hair shaft down to contact the surface of the medium Hairs for inoculation often can be selected by choosing those that fluoresce with a Wood’s light Examination of some of the plucked hairs... excessive agitation of the sample once within the tube Hemolysis can interfere with a number of diagnostic tests and should be avoided Make an effort to have the animal fast for a minimum of 12 hours before the collection of blood samples to avoid postprandial lipemia Lipemia is attributable to metabolic disorders (pancreatitis, diabetes mellitus) and to recent meals and adversely and artifactually can... from cells within 45 minutes of sample collection (venipuncture) Special vacuum vials are available that produce a strong barrier between the clot and the serum so that it is not necessary to draw off the serum into a separate vial Clotting of the blood and retraction of the clot occur best and maximum yields of serum are obtained at room or body temperatures Refrigeration of the sample impairs clot... Many clinical chemistry procedures can be performed on plasma and on serum The advantage of using plasma is that separation of cells can be accomplished immediately after centrifugation or sedimentation, without the need to wait for clot formation and retraction The disadvantage of plasma is that the presence of the anticoagulant interferes with many of the chemistry assay procedures Plasma is less... the animal in lateral recumbency, and clip the hair over the area of the iliac crest Surgically prepare the site To aspirate marrow, have the needle enter the widest part of the iliac crest and stop the needle just after penetration of the bone Remove the stylet, place a 12-mL syringe on the needle, and aspirate 0.2 mL of marrow Alternatively, the head of the humerus offers easy access to abundant bone... of a mannitol plate for each eye Also place material into thioglycolate medium 4 A03751-S04 11/11/05 468 4:13 PM Page 468 4 DIAGNOSTIC AND THERAPEUTIC PROCEDURES Alternatively, use one of the commercial multiple-media plates Make two conjunctival scrapings and stain one with Gram stain and the other with Giemsa stain Skin cultures Cultures made from the surface of the epidermis or open ulcers are of. .. inoculated deep into thioglycolate medium for transfer and subculture With anaerobic organisms, it is especially important to make a smear and a Gram stain and to record all morphotypes present and the relative numbers of each (Box 4-3) Additional Reading Dow S: Diagnosis of bacteremia in critically ill dogs and cats In Bonagura J, editor: Current veterinary therapy XII Small animal practice, Philadelphia, . 0 .23 6 19 6.3 0 .24 9 20 6.7 0 .26 3 22 7.3 0 .28 8 24 8 0.315 26 8.7 0.341 28 9.3 0.367 30 10 0.393 32 10.7 0.419 34 11.3 0.445 *Mutiple types of pediatric polyurethane. 0.066 6 2 0.079 7 2. 3 0.0 92 8 2. 7 0.105 9 3 0.118 10 3.3 0.131 11 3.7 0.144 12 4 0.158 13 4.3 0.170 14 4.7 0.184 15 5 0.197 16 5.3 0 .21 0 17 5.7 0 .22 3 18 6 0 .23 6 19